Anyone have an idea where this part goes, somewhere near the consumer battery? Any ideas would be greatly appreciated.... Thanks!

 

Anyone have an idea where this part goes, somewhere near the consumer battery? Any ideas would be greatly appreciated.... Thanks

 

I don't think I have it in my car. Do you see a part number on it? Did you buy your car used? I guess somebody left it in your trunk which actually didn't belong there.

 

CPDay- thank you for all the research and time you spent on this issue. My question is simple, did you disconnect both batteries and install an OBD Memory Saver when you disconnected the fuses to bench test?

 

sgort2- Good question. I know for certain that I did disconnect both batteries and I did not use any type of memory saver. I had to reset the convenience items (seat positions, window close position, etc) afterward. I don't recall losing any OBD data, but that was some years ago and my recollection could be wrong. I have thought that the OBD data was non-volatile. Perhaps someone else will chime in re this question.

 

They only reason you would want to disconnect both batteries is if you wanted to test the fuse when it's still in the circuit. Not advisable though. Pull them out and test them when you know for sure no load is on the fuse.
I didn't use a memory saver and everything worked just fine after testing the fuses but remember this is to the best of my knowledge. Maybe something was lost but definitely not something major or I would've had noticed it.

 

Thanks for all of the great info everyone, I just put a brand new battery in the trunk, to no avail. Looks like I’ll be digging out the fuses when I have a free day. Until then I’ll drive the car and see if the “red” goes away. I’m sure that would be way to easy.
Ill let you know what happens, one quick question that you guys might know off hand, my mechanic has a super scanner, is this something that can be checked with it?
Thanks again for all of the great info!

 

FWIW, and I admit I didn't read every last post, so I don't know if this has been mentioned, but Advance Auto carries the starter battery. The battery size is V4 and it is identical to the factory battery except it says AutoCraft Gold instead of Mercedes Benz. Even the manufacturer's stamp in the side of the battery was identical. $165, but you usually get 15% or 20% off when ordering on-line and picking up in the store.

 

Yep - I have that same Advance Auto battery. I've been very happy with all the batteries I've bought from them over the years.

 

O’Reilly Super Start Extreme Group Size V4 Top Post Battery Part # V4EXTJ Line: SSB, is also a direct replacement @ $160.

 

bentonmike- It can't hurt to try a scanner, especially if it is done for free, but I wouldn't be optimistic. I have a Star Diagnostic System now, but I didn't back when the Red Battery Warningoccured. I am not confident that it would have helped beyond just reporting the error. CPDay

 

It looks like all the V4 batteries come out of the same factory.

 

@CPDay thank you for all the info! I'm about to tackle this hopefully next week. I will keep you and the rest updated.... hopefully the issues go away. A little backstory. I got my 2003 SL500 ridiculously cheap due to these gremlins. So I noticed my keyfob didn't work from far. If you get really close and press it multiple times it unlocks the car. Replaced the batteries in the fob and the same scenario persists. Thought it was the EIS but the ignition switch recognizes it every time with no issues. I also have the "red battery warning" and the blue "ABC" light although the suspension is fine with no leaks or sagging. The top won't operate because of the battery warning I believe. I don't see any issues with the top itself (although I did notice the trunk actuators that hold it up don't stay up.) With that being said I thought the voltage regulator was the culprit. I ordered the genuine Bosch regulator, took me couple of hours to free because I was having a hard time taking the cover off, although I had already took off all the necessary screws. I forcefully pulled it off and I noticed that parts where the plastic touches the alternator (I have pictures) are melted and was stuck/fused with the alternator (maybe that's the root of the issue?) Anyways I changed the regulator ( the original looked fine) connected the starter battery first and then the rear one and still had the same red battery light. At this point I'm concerned with the alternator entirely being at fault, but the car starts fine and runs good. Now I haven't driven the car in about 3 days and had the "consumer message" pop up today. I drove to work like that. I will see if the message will reappear when I turn it on again. Now that I saw this very informative thread I'm considering changing the fuses in the footwell area. Now do you guys suggest changing the alternator AND fuses at the same time, or troubleshoot one by one. By changing fuses first or vice versa? Appreciate the help.

 

I wouldn't change an alternator without first measuring the voltage it put out. Measure it at the cables attached to the rear battery.

 

One surprising thing that I learned from my “red battery warning” incident was that the SL will continue to start happily through weeks of normal use, even if the starter battery is not receiving any charge. You need to determine if yours is getting charged. If I was in your situation, I would first dig down to the passenger footwell fuses, REMOVE BOTH fuses, check each one’s continuity, and replace with new ones, if needed. That MIGHT fix your red battery warning problem. It requires some gymnastics and contortions, but it won’t cost much.

i am not certain that I understand your “blue ABC light” issue. Where on the dash and when do you actually see this light? ABC System troubles can get serious and expensive, if not addressed. I might not wait on that one.

Regarding the key and the non-operating top... Whoa, you probably need some other help from folks on this forum.

Let us all know if you check the footwell fuses, in any case. GOOD LUCK!

 

Before I try to tear my footwell apart, if both batteries show increased voltage with the engine running, can I rule out a blown fuse?

 

Oops, sorry for the double post

Before I try to tear my footwell apart, if both batteries show increased voltage with the engine running, can I rule out a blown fuse?

 

You can positively rule out the fuse that CPDay replaced which is in the charge circuit for the starter battery, but I'm not sure of others. Reading diagnostic codes from the vehicle power supply controller will explain why the fault indication is on.

 

Is star diagnostics the only way to read the codes or are there cheaper alternatives?

 

I have an iCarsoft 980 which costs c. $115. Generally, it can read codes from all systems, though the last time I tried to read an ABC controller it failed.

If the scope of your diagnostic work is to simply retrieve codes to gain an idea of what is wrong and let a professional handle most repairs, then an iCarsoft will likely serve you well. Otherwise I suggest buying Star Diagnosis. A setup can be had for as little as $250.

Star Diagnosis can read codes like iCarsoft, of course. But unlike iCarsoft it provides an explanation of the code and provides a step-by-step procedure for fixing a problem. In addition to the diagnostic software, you also get the Mercedes WIS, electrical schematics, and the parts catalog.

 

I concur. I didn’t have a Star Diagnostic System back when this thread started, but I have been using one ever since. It has paid for itself many times over and for me, made SL550 ownership affordable.

 

Thank you for your input!!! Now I’m back again guys.... sorry for the delay. I bought the fuses but never got to work on it until yesterday and today. It was a PITA to take out the millions of layers of carpet and equipment to reach these infamous fuses but I got to it. Removed both like CPDay said. Tested both (which were clear.... are all original fuses.. are the originals clear?) and both came out with good continuity. Replaced both and STILL have the issue. Now. What I went and did BEFORE taking the fuses, I checked and noticed my front battery registered 12.5 volts and the rear battery registered 11.7 volts about. Now I did not drive the car the day before that but I did turn it on and had it running for a few minutes that day. Either way I disconnected both batteries and charged the rear one while I tackled the fuses yesterday. I plugged everything back today earlier including the fully charged battery and the car started up normal like it has many times before. Now one thing I do want to point out, is that every time I start the car the illumination from the gauge goes brighter and back to a lower dim instantaneously. Is that normal? Or a sign of the recurring issue????? Anyway the car started the same way and the Red Battery Icon comes up first right away, followed by the blue/clear ABC “visit workshop” message ( not the red one ) and a “bulb icon visit workshop” message as usual. Now I’m gonna do some digging tonight to see what else it could be...... now what other culprits can I rule out? The front battery has always been fine and is the MB brand. The fuses can’t be a culprit anymore since they’re new and the old had continuity. The rear battery was slightly discharged prior to doing this job and fully charged before installing again today. tomorrow I’ll see how the voltage reads... now i stopped driving the car this last month since I have a new daily at the moment. So every 2 or more days that the SL was not turned on/driven I would get the “ consumers off “ message. So I will check tomorrow the reading and the next day to see if it will replicate with the now fully charged battery. Also this rear battery apparently was new when I purchased the vehicle. It is a cheap brand battery. So I think this might be a good suspect to follow up on. Now the alternator Seems to be working fine because before doing this job both batteries charged over 12.5 volts. The front charged more than 13-13.5ish, and the rear was at 12.0-12.5 ish. After installing the rear fully charged battery and connecting the front one again, the rear registered 13.0 volts about and the front at 14 volts. Now though.... I did replace the voltage regulator a couple of months ago thinking it would fix this “red battery” issue. Of course it did not. But in the process I struggled to take off the cover. I come to find out once I removed it. Plastic parts that connected with the metal in one section of the alternator had somewhat melted and got stuck to the metal making it difficult to remove. I thought I was odd but put the new regulator and put it back together with no issues. (Could that be a suspect? Or the culprit that shorted something else?) anyways so from my research I’m left with one more suspect which could be the Vehicle Power Supply Module aka the N82/1??? Is that a correct assumption? At this point I feel like I have no choice but to replace that unless it can’t be either the alternator (which I don’t think) or the cheap knock off rear battery. Any inputs??? Thank you for reading!

 

I searched for the condensed Readers Digest summary for this post, and when I didn't find one I cst straight to he chase, and that landed me here!!! Somewhere along the way did you read codes for N82/1? There are only about ten ones possible, and one is a self-diagnosis that it has failed.

 

ok so I don’t have a computer to check the codes but at work I have been researching more about this issue. Now I have not mentioned that when I bought the car the Fuel Gauge doesn’t work, the key sometimes works to unlock and lock from some distances. The windows don’t roll down softly when opening and closing the doors and a battery drain from the G1 battery.... so I came upon other threads discussing that those are bad SAM (rear SAM specifically) symptoms. Now along with the red battery light I’m assuming there’s something with F33, the 3 fuses in there and the connections to the SAM that cause all of the headaches in this car. I will look into it tomorrow as I get off work and will update!

 

To anybody out there still reading, I have fixed my “Red Battery Light” issue. Without going in too deep. I came to find that there was a battery drain, but prior to that my assumption was that the rear battery was faulty and/or my alternator as well. After much research I came to find out that many of the issues I stated above (gas gauge faulty, alarm weak, seats ventilating out of nowhere, lighting issues...) came from a Rear SAM malfunction. After taking it out I saw corrosion on the pins. Opened the board and cleaned it.( It was horrible and will post pictures) put it all together hoping it wasn’t gonna work. It looked beyond repair. But thank God it did! All the issues were resolved as far as SAM. Meanwhile I did that... I took both batteries and charged them fully. Voila the Red Battery Message was gone!!! After driving a couple of minutes I noticed on my icarsoft that the batteries were not being charged and the message came back again. I am replacing the alternator as I speak and all issues should be resolved. I wanna thank all here for starting this wild rabbit hole chase that led me to fix many problems with a lot of DIY!